Stabilization of halogenated hydrocarbons



Patented Apr. 18, 1933 11m n STATES PATENT OFFICE CHARLES ROBERTS HARRIS, OF NIAGARA FALLS, NEW YORK, ABSIGNOB TO THE BOSSSLER & KABSLACHER ICAL COMPANY, OF NEW YORK, N. Y A CORPORA- 'IION OF DELAWARE STABILIZATION OF HALOGENA'IED HYDROCABBONB Ho Drawing.

This invention relates to the stabilization of chlorinated hydrocarbons.

Com ounds of this class, for example, trichloret ylene, tetrachlorethane or methylene 5 chloride, tend to undergo decomposition during storage with the formation of substances of acid character. This decomposition makes the product objectionable for such purposes as extraction'and produces an acidity that corrodes storage tanks. While this type of decomposition is more or less general in all chlorinated hydrocarbons, it has been found that materials added to 16 and as such may be very satisfactory for the stabilization of one or more compounds but are not necessarily satisfactory for all others.

Such varied substances as xylene, phenols,

20 toluene, resorcinol, guaiacol, thymol, methanol and carbon tetrachloride, have been proposed as stabilizers for chloroform. W e

ave found that these materials are'not of general applicability to all chlorinated hydrocarbons but that the action of the inhibitors is specific in efiect and of a catalytic nature. Some of these substances are very poor stabilizers for certain chlor-hydrocarbons, and must be used in large amounts.

Such amounts of stabilizer renders the chlorinated hydrocarbon useless, for example in certain extractions; poor stabilization results in acidity.

Hydrocarbons, for instance gasoline, have been proposed as stabilizers for trichlorethylene. These are objectionable when the solvent is used in certain processes because a comparatively large amount of gasoline is 4 required to stabilize and the hydrocarbon heavy ends may be deposited in and contaminate the product. v

The object of this invention is to provide an efiective stabilizer for chlorinated hydrotb carbons which need be applied only in small Application filed march 8,

romote stability behave as inhibitory cata ysts 1931. Serial N0. 519,884.

concentrations and which does not'develop an objectionable odor.

I have discovered that chlorinated hydrocarbon decomposition, with the resultant development of acidity, may be prevented by the addition of amylene in appropriate amounts.

My process of stabilization consists in mixing a small amount, for instance, 0.0001- 01%, of the stabilizer with the chlorinated hydrocarbon. A preferred method of mixing consists in transferring the required amount of a strong stock solution of amylene, made up by weight to known concentration in the chlorinated hydrocarbon to be stabilized, into a known volume of that chlorinated hydrocarbon. Other methods according to particular situations that might arise, will readily suggest themselves to one skilled in the art.

To measure the instability of a chlorinated hydrocarbon, I have determined the acidity developed over various periods of time.

Ewamples m A number of chlorinated hydrocarbons were stabilized with small concentrations of amylene as shown in the table below. The formation of acidity in some cases was not only inhibited, but was even reduced. On the other hand the stabilizing action of amylene varies from one chlorinated hydrocarbon to others similar thereto as the table beso low shows. This invention is particularly applicable to trichlorethylene, tetrachlorethane, methylene chloride and perchlorethylene.

To measure instability the acidity developed over various periods of time has been determined. In the following table the acidity is stated in terms of the number of cubic centimeters of 0.01 normal sodium hydroxide solution required to neutralize 25 cc. of W thechlorinated' hydrocarbon, using phenolphthalein as indicator.

mobilization with amulene Maxi- Oman Initial De mum Chlorinated h dxocarbon tmtlon o! mbmm m m 'Irlchloroth lone None 0.8 a 28 1 0 y o. 05% o. a a a Tetraohlorethmic None 0. 2 89 too 0 0. 06% 0. 2 at t. 7 Methylene chloride--. None 0. 8 57 275 o 0. 1% 0. 8 M 0. 0 Perchlorethylene None 0.2 to 150 0. 05% o. a a5 4 N one 0. 2 53 83 0.05% 0. 1 53 80 This invention is not limited to specific roportions of stabilizers. 0.0001 per cent y weight of amylene for any one of a numher of chlorinated hydrocarbons, according to the proposed utility of the composition, is a quite markedly eifective. Practical purposes may demand as high as about 1.0 per cent. The amount added will depend on the spew cific stabilizing agent, the particular compound to be stabilized the problem of its use and the degree of stability desired.

I claim: 1. A composition of matter comprising a an chlorinated hydrocarbon and stabilizing amounts of amylene.

2. A. composition of matter comprising a chlorinated hydrocarbon of the group comprising methylene chloride, trichlorethylene,

35 tetrachlorethane, dichlorethylene and perchlorethylene and stabilizing amounts of amylene.

3. A composition of matter comprising a chlorinated hydrocarbon and from about M 0.0001% to about 1% by weight of amylene.

t. A composition of matter comprising methylene chloride and stabilizing amounts ot' amylene.

5. A composition of matter comprising methylene chloride and from about 0.0001% to about 1% by weight of amylene.

6. A composition of matter comprising trichlorethylene and stabilizing amounts of am lene. 5w A. composition of matter comprising trichlorethylene and from about 0.000196 to about 1% by weight of amylene.

'8. A composition of matter comprising tetrachlorethane and stabilizing amounts of w amylene.

r 9. A composition of matter comprising tetrachlorethane and from about 0.0001% to about 1% by weight of amylene.

Signed at Niagara Falls, in the county of W Niagara and State of New York, this 20th day of February, A. D. 1931.

CHARLES ROBERTS HARRIS. 

